What is henna, anyway?
A luster-enhancing botanical famously used by Cleopatra, henna is a powder derived from the ground leaves of the Middle Eastern Lawsonia inermis shrub. In its natural state, the dye is a deep, rich red, but it can be combined with other plant-based hues for a wide range of shades. The catch: Henna coats hair shafts and may disrupt the effectiveness of perms and permanent dyes.

When you're in the mood for a makeover, there's nothing like the instant gratification of an at-home dye job. Fortunately, you can transform your appearance using milder products that minimize contact with potential carcinogens. Sure, they're not perfect—it's impossible to achieve enduring color with zero chemicals—but natural options are on the up-and-up. Whether you choose a permanent, semipermanent, or temporary option, always remember to test for allergies by applying a small amount behind your ear and letting it sit for 24 hours, and dye a few strands before you commit to the color.

The long laster
Permanent dyes open and penetrate the cuticle to infuse your locks with color that stays vibrant until hair grows out. Many products, though, contain resorcinol—a known irritant—or petroleum-based coal tar to make color last longer. "In lab studies, contaminants such as benzopyrene in coal tar have been associated with cancers," says Kristan Markey, a chemist and research analyst for the Environmental Working Group. "Resorcinol is a possible endocrine disrupter, but long-term risks are less clear." For a more healthful approach, search out brands that use minimal amounts of ammonia, hydrogen peroxide, coal tar, and parabens. "Changing hair is complex chemistry," says Markey. "You're doing reactions, and you need to know what's in your products." Remember that ammonia- and peroxide-free dyes won't lighten natural hair color and are best used for darkening and blending gray.

Color from the kitchen
Brunettes. Fresh rosemary will bring out dark hair's warm, rich tones. Steep 2 tablespoons rosemary leaves in boiling water for 30 minutes. Then strain, rub the herbs into clean hair, and let it set for the rest of the day. To augment auburn highlights, substitute calendula for rosemary and follow the same procedure.
Brunettes and redheads. To enhance red and brown, mix 2 teaspoons henna powder with 1/2 to 1 cup brewed coffee and thoroughly rinse through hair. Stir in one egg or 1 to 2 teaspoons olive oil before applying to keep hair from drying out.
Blondes. Lighten your locks by boiling 1/2 cup dried chamomile flowers for 30 minutes. When the brew cools, strain and rinse your tresses with the liquid, then sit in the sun for one hour or longer.

—Christy Mercer

The fast and easy
To steer clear of petroleum by-products and other carcinogens altogether, look for a semipermanent (sometimes called temporary) dye or color-enhancing rinse that contains botanical hues that coat hair cuticles rather than opening them. Semipermanent natural shades are perfect for those who want to test a less dramatic look: Chamomile and lemon extract make blond tones richer; henna enhances red highlights; and walnut or coffee bean extract will bring out brunettes' depth. No matter what color you're going for, look for products that contain sunflower seed extract to help protect color from fading. Semipermanent tints will last for four to six weeks, while rinses need to be reapplied with every wash.